Stabilization of organic substances



Patented June 21, 1949 um'rso s'rA-ras PATENT OFFICE STABILIZATION OF ORGANIC SUBSTANCES George H. Denison, .Ir., Oakland, and Paul 0. Congilt, Berkeley, Caill., auignors, by mesne assignmenta, to California Research Corporation, San

Francisco, Calif... a corporation of Delaware no Drawing. Application February 21, 1945, Serial No. 519,169

.6 Claims. (Cl. 252-45) This invention relates to the improvement of organic substances which are susceptible to oxidation; more particularly, it relates to the, stabilization of mineral lubricating oils against oxidation. This application is a continuation-in-part of our copending application Serial No. 486,306, died May 10, 1943 issued April 16, 1946, as United States Patent No. 2,398,416.

We have found that certain low molecular weight aliphatic selenium compounds, when added in small amount to organic substances which are subject to oxidation, strongly inhibit the oxidation of such organic substances.

The selenium compounds of the invention are aliphatic seleno ethers or monoselenides containing not more than 14 carbon atoms and having in the molecule the group wherein the two carbons atoms shown are aliphatic carbon atoms. Examples of suitable aliphatic seleno ethers are dimethyl seleno ether (CHaSe-CHa), di-ethyl seleno ether (CaHs-Se-Cafls) di-n-propyl and di-isopropyl seleno ethers (CaH'z-Se-CaH'l) di-n-butyl and di-isobutyl seleno ethers (C4Hn-SeClHe) di-n-amyl and di-isoamyl seleno ethers (CsHn-SeCsHu) di-nhexyl and di- -isohexyl seleno ethers (CeHn'Se-CeHu) di-hepyl seleno ethers (c-imsse-cqmo and dibenzyl seleno ether (CaHe-CHa-Se-CHa-Cafis). Mixed seleno ethers may also be used: e. g., methyl propyl seleno ether and ethyl hexyl seleno ether. The aliphatic radicals may be alkyi, alkylene or saturated or unsaturated cycloaliphatic radicals, and the aliphatic radicals maybe subf 'stituted. by non-hydrocarbon groups or by arematic groups.

Broadly stated, therefore; the invention resides in the employment, in an oxidizable organic sub- I stance, of a small amount, 'sumcient to inhibit oxidation, of a compound (or mixture of compounds) of the formula R-'-SeR1 wherein R and R1 are hydrocarbon (or substituted hydrocarbon) groups containing, in toto, not more than 14 carbon atoms and wherein the attachment of each of the groups R. and R1 to the selenium is through an aliphatic carbon atom.

The preferred seleno ethers are the diamyl, dihexyl and dibenzyl seleno ethers.

The seleno ethers of the invention can be prepared by methods well known in the art. The simplest method of preparing symmetrical seleno ethers is by condensing a chlorinated hydrocarbon, such as methyl, ethyl, propyl (normal or iso), butyl (normal or iso), amyl (normal or iso) hexyl (normal or iso) or benzyl chloride with sodium selenide (NazSe).

The reaction occurring is as follows:

A mixture of chlorinated hydrocarbons, such as a mixture of isomeric amyl chlorides, may be used instead of a pure chlorinated hydrocarbon. Mixed seleno ethers, such as methyl propyl seleno ether (CHa-Se-CaHr) and methyl benzyl seleno ether (CHa-Se-CHz-CeHs) can be prepared by condensing sodium hydrogen selenide (NaHSe) with a chlorinated hydrocarbon to produce a seleno mercaptan, the reaction being then converting the seleno mercaptan'to a metal seleno mercaptide, e. g., sodium seleno mercaptide (R-Se'Na) and condensing the seleno mercaptide with a chlorinated hydrocarbon difiering from that used in the first reaction, the second reaction bein wherein R and R are different radicals.

By way of example. data on the preparation of diamyl seleno ether are given below:

3 mols (319 grams) of a mixture of amyl chlorides (Sharples mixed amyl chlorides) and 1% mols (187 grams) of sodium selenide (NazSe) were refluxed together in 1500 milliliters of 95% j alcohol for 10 hours. The reaction mixture was diluted with an equal volume of water and extracted with petroleum ether. The petroleum ether was removed from the extract by heating on a steam plate and the residue (299 grams) was fractionated at 10 mm. mercury pressure into five fractions boiling as follows: ('1) 182- 196 F.; (2) 197-201 F.; (3) 202-229 R; (4)- 231247 F.; (5) 247-255 F. The first three.

fractions, boiling from 182 F. to 229 F., were all found to contain very nearly the same amount of selenium, which amount was very close to the theoretical selenium content of diamyl seleno ether (CsHn-SHsHu), which is 35.7%. The

3 last two fractions contained substantially more selenium, or 43% and 51%, respectively. The theoretical selenium content of diamyl diselenide (CIHIISGQCBHH) i 52.7%; hence, it follows that the last two fractions contained substantial amounts of diamyl diselenide, the last fraction being substantially pure diamyl diselenide.

The first three fractions were combined and the combined fractions were used as an antioxidant. This combined product is a mixture of isomeric diamyl seleno ethers, resultin from the use of a mixture of isomeric amyi chlorides in preparing the seleno ether.

The seleno ethers of the invention are in some cases effective antioxidants at concentrations as low as 0,0001%. Ordinarily, concentrations of about 0.1 to 2% will be used, but larger and smaller amounts may be used as the occasion demands. Concentrations in excess of 5% are ordinarily unnecessary, except in forming a concentrate of the seleno ether with mineral lubricating oil or other organic substance for later blending with the substance to be stabilized to produce a finished product. In such concentrates the amount of seleno ether may be as high as 50% or more.

All percentages herein stated are percentages by weight based upon total product (e. g., finished lubricant) unless otherwise stated.

The following specific example will serve to illustrate the practice and advantages of the invention:

Diamyl and dibenzyl seleno ethers were used to inhibit oxidation of a medicinal grade of white oil. The diamyl seleno ether was the mixture of isomeric diamyl seleno ethers described above. The dibenzyl seleno ether was the compound described in Beilsteins Handbuch der Organischen Chemie, fourth edition, volume VI, page 4'70. The dibenzyl seleno ether had a melting point of 45.5" C. The white oil was a very highly refined mineral oil of lubricatin viscosity. The diamyl seleno ether was used in the amount of 0.0568% and the dibenzyl seleno ether was used in the amount of 0.062%. The oxidation test, known as the Oxidator Test, was carried out in apparatus of the type described by Dornte in Industrial & Engineering Chemistry, vol. 28, page 26 (1936). In this test, oxygen at atmospheric pressure is bubbled through the oil, which is maintained at 340 F. The extent of oxidation of the oil is measured by the amount of oxygen absorbed by the oil, and the time in hours required for 100 grams of oil to absorb v 1200 cc. of oxygen (S. T. P.) is called the Induction period. Induction periods of base oil and inhibited oils were as follows:

Induction Period Base 011 0.05 Base oil 0.0568% diamyl seleno ether hours.. 0.7 Base oil 0.062% dibenzyl seleno ether do 1.1

as unity:

Dicetyl thioether 1 Diamyl seleno ether 3.8 Dibenzyl seleno ether 1... 6.4

This comparison is all the more surprising when it is considered that diamyl seleno ether (moi. wt. 221) and dibenzyl seleno ether (moi. wt. 261) are much more volatile than dicetyl thioether (mol. wt. 482), and are evaporated from the oil during the test to a much greater extent than dicetyl thioether.

The seleno ethers of the invention are also more advantageous antioxidants than the di-, triand other polyselenides (R-SEr-Ri, where R and R1 have the same significance as above and m=2, 3, etc.), in that they are more easily prepared and in that they are more stable than the aforesaid di-, triand higher polyselenides.

One or more seleno ethers of the invention may be used as the only added material present in an oxidizable organic substance or they may be used in conjunction with other additives. For example, the seleno ethers of the invention may be used advantageously in mineral lubricating oils in conjunction with any of the known metal salts of organic acids and/or metal salts of organo substituted inorganic acids. These salts are used to improve various properties of lubricating oils, such as detergency, stability against oxidation, film strength, etc. Examples of such metal salts are calcium, barium, zinc and aluminum salts of cetylphenol; calcium, barium, zinc and aluminum salts of diamyl diphenol monosuliide, calcium,

barium, zinc and aluminum salts of monoand dicetyl esters of phosphoric acid; calcium, barium, zinc and aluminum salts of monoand dicetylphenyl esters of dithiophosphoric acids; calcium, barium, zinc and aluminum salts of naphthenic acids; calcium, barium, zinc and aluminum salts of oil-soluble petroleum (mahogany) sulfonic acids; calcium, barium, zinc and aluminum salts of dibutyl dithiocarbamic acid; calcium, barium, zinc and aluminum salts of reduced petroleum nitrogen base dithiocarbam'ates of Miller and Rutherford United States Patent No. 2,363,012. Other metals (e. g., sodium, lithium, magnesium and cobalt) and other acid radicals (e. g., aryl carboxylic acid, fatty acid, aliphatic polycarboxylic and thiophenol radicals) may be used instead of the aforementioned calcium, barium, zinc and aluminum metals and the aforementioned phenate, phenate sulfide. phosphate, thiophosphate, naphthenate, sulfonate and dithiocarbamate radicals, respectively. Thus, from 0.1 to 2% of seleno ether and from 0.1 to 2% of metal salt may be added to mineral lubricating oil, or greater amounts may be used to form a concentrate or stock solution. Further details concern.- ing the conjoint use of seleno ethers and metal salts of organic and/or organo substituted inorganic acids in oils of lubricating viscosity, such as particular combinations of additives, results obtainable by such conjoint use, etc., may be found in our aforesaid copending' application Serial No. 486,306 issued April 16, 1946 as Patent No. 2,398,416, and such details are incorporated herein by reference. E

The seleno ethers of the invention may also be used advantageously in turbine lubricants and other industrial lubricants which are used to lubricate metal surfaces under conditions (such as intermixture of the lubricant with water) which promote rusting and corrosion of ferrous metal surfaces. It is now the practice to add to such lubricants both a corrosion or rust inhibitor and an antioxidant. Examples of corrosion or rust inhibitors are lauryl acid maleate and the products of condensing high molecular weight olefins with maleic anhydride and hydrating the resulting I condensation product. The said olefln-maleic anhydride condensation-hydration products are described in Moser, United States Patents Nos. 2,124,628 and 2,133,734. a The seleno ethers of the invention are especially advantageously used in turbine lubricants and others of the class just described, in conjunction with rust or corrosion inhibitors such as lauryl acid maleate or on of the aforesaid olefln-meleic anhydride condensation-hydration products. The seleno ethers cooperate with the -rust or corrosion inhibitors to produce an oil which is both stable and rust in- 4 hibitlve. Amounts of seleno ether ranging from about 0.1% or less to 2% or more and of rust or corrosion inhibitors ranging from 0.005% or less to 2% or more, preferably 0.05 to 0.5%, may be used.

Besides mineral oils of lubricating viscosity, many other oxidizable organic substances may be stabilized by the sciatic ethers of the invention; for example, fats, fatty oils, rubber, mineral oilsoap greases, aldehydes, ethers, terpenes, mencaptans and phenols.

We claim: 1. A lubricant comprising a major proportion of a mineral lubricating oil which is susceptible to oxidation and a small amount, suflicient to inhibit oxidation of said lubricating oil, of a monoselenide containing not more than 14 carbon atoms and having in the molecule the structure Jnariracvauo dialkyl monoselenidc is dihexyl seleno' ether. I

5. A lubricant comprising a major proportion of amineral oil of lubricating viscosity and about 0.1 to 2% by weight based on finished lubricant of dibenzyl monoselenide. A

6. A composition of matter comprising a major proportion of a normally liquid organic material of lubricating viscosity whichis susceptible to atmospheric oxidation and deterioration and, dissolved therein, a small amount, sufficient substantially to inhibit said oxidation and deterioration, of a monoselenlde containing not more than fourteen carbon atoms and having in-the molecule the structure wherein both carbon atoms are aliphatic carbon atoms. 7

w GEORGE H. DENISON, Ja.

PAUL C. CONDIT.

REFERENCES CITED The following references are of record in the OTHER REFERENCES Journal Chem. vol. 12, pages 363-366 (1935). Proc. Indiana Acad. Sci., vol. 43, pages 72-98 Certificate of Correction Patent No. 2,473,510. June 21, 1949. GEORGE H. DENISON, JR., ET AL.

It is hereby certified that errors appear in the printed specification of the' aboir numbered patent requiring correction as follows:

Column 5, line 42, claim 3, and column 6, line 1, claim 4, for seleno ether read monoselen'ide'; same column 6, line 6, beginning with 6. A composition of matter strike out all to and including the word and period atoms. in line 19, comprising claim 6; in the heading to the printed specification, line 9, for 6 Claims read 5 Claims; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 29th day of November, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommz'sz'oner of Patents.

Certificate of Correction Patent No. 2,473,510. June 21, 1949.

GEORGE H. DENISON, JR., ET AL. 7 It is hereby certified that errors appear in the printed specification of the'above numbered patent requiring correction as follows:

Column 5, line 42, claim 3, and column 6, line 1, claim 4, for seleno ether read monoselemlde; same column 6, line 6, beginning with 6. A composition of matter strike out all to and including the word and period atoms. in line 19, comprising claim 6; in the heading to the printed specification, line 9, for 6 Claims read 5 Claims; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 29th day of November, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommisz'oner of Patents. 

